Supplementation with sunflower or soybean oil: Ruminal fluid fatty acid profile in a Rusitec system.

C. Cajarville

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06-22-2020

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Abstract:

M133
Supplementation with sunflower or soybean oil: Ruminal fluid fatty acid profile in a Rusitec system.
G. Casarotto¹, A. Britos¹, S. Carro², I. Vieitez³, C. Dauber³, C. Cajarville*¹. ¹Departamento de Producciï¿½n Animal (IPAV), Facultad de Veterinaria, UdelaR San Josï¿½, Uruguay, ²Departamento de Ciencia y Tecnologï¿½a de los Alimentos, Facultad de Veterinaria, UdelaR Montevideo, Uruguay, ³Departamento de Ciencia y Tecnologï¿½a de Alimentos (CYTAL), Facultad de Quï¿½mica, UdelaR Montevideo, Uruguay.

The aim was to evaluate the effect of including 2 levels of sunflower or soybean oil to a forage-based diet on the rumen fluid fatty acid (FA) profile. In a Rusitec system 5 diets were evaluated: C (control, 65% alfalfa hay and 35% concentrate; 16% CP, 33% NDF, 3.4% EE), SF6 (C + sunflower oil added until reaching 6% EE of diet DM), SF7.5 (C + sunflower oil added until reaching 7.5% EE of diet DM), SB6 (C + soybean oil added until reaching 6% EE of diet DM) and SB7.5 (C + soybean oil added until reaching 7.5% EE of diet DM), incubating 8g of DM in Nylon bags. Inoculum was obtained from 2 rumen fistulated cows fed with the C diet and McDougall artificial saliva was infused at 3%/h. Three runs of 10 d (5-d adaptation period plus 5 d of sampling) were performed. Samples were taken from fermentation units at the same time as the bags were changed. Ruminal fluid FA profile was determined by GC. Data were analyzed according to a repeated measures model and means separated by LSMEANS. Sunflower and soybean oils inclusion resulted in a decrease of C16:0 (P = 0.003) and increased levels of C18:1 t11 (trans-vaccenic acid, TVA; P < 0.001). Diets SF7.5, SB6 and SB7.5 decreased the concentration of saturated FA with respect to control (P = 0.041; Table 1). Results indicated that adding sunflower or soybean oils up to 7.5% EE of total DM in the diet, did not increase C18:2 c9 t11 (CLA) levels, but increased its precursor TVA and may decrease saturation process.Table 1. Rumen fluid FA profile (g/100 g of FA)

Fatty acid	C	SF6	SF7.5	SB6	SB7.5	SEM	P-value
T	D	T ï¿½ D
C16:0	12.12^a	9.75^b	9.10^b	9.08^b	9.25^b	0.826	0.003	0.643	0.990
C18:0	3.75	3.51	2.87	2.58	3.14	0.666	0.261	0.908	0.669
C18:1 t11	0.51^b	0.75^a	0.75^a	0.73^a	0.75^a	0.040	<.001	0.545	0.877
C18:1 c9	40.69	43.05	44.42	44.97	44.55	1.794	0.067	0.773	0.713
C18:2 c9,c12	30.07	30.94	28.87	28.20	28.80	0.846	0.125	0.181	0.981
C18:3n-3	0.48	0.36	0.24	0.32	0.21	0.093	0.268	0.572	0.786
C18:2 c9,t11	0.41	0.12	0.17	0.33	0.19	0.107	0.357	0.475	0.730
SFA	20.21^a	18.85^ab	17.66^b	17.77^b	18.31^b	1.166	0.041	0.689	0.579
MUFA	40.74	43.13	44.48	45.01	44.61	1.824	0.067	0.775	0.718
PUFA	30.55	31.30	29.11	28.51	29.01	0.885	0.112	0.214	0.988

Keywords: rumen fermentation, lipids, fatty acid.